Consider the recurrence x_k+2 = ax_k+1 + bx_k + c where c may not be zero. If a + b is not equal to 1 show that p can be found such that, if we set y_k = x_k + p, then y_k+2 = ay_k+1 + by_k. [Hence, the sequence x_k can be found provided y_k can be found] First of all, sorry about the messiness, I don't know how to use LaTeX. Now, this is the question exactly as it is from the question sheet. My problem is, I don't understand the question. And its kind of really hard to start the question without understanding it . My biggest concern is, what the heck is p and where does it come from? The way I read it, p is just -c. Thx in advance for any help.